The present invention relates to an automotive air-conditioner.
The prior art automotive air-conditioner of the type that is installed under the instrument panel of a passenger car is generally of the structure which is schematically illustrated in FIG. 1 of the accompanying drawings. More specifically, the prior art air-conditioner comprises a housing formed by a duct 20 having an upstream end connected to a discharge port of a fan casing 100 which accommodates a centrifugal fan 104 having a large number of vanes. The fan casing 100 is provided with a fresh air inlet 101 and a recirculated-air inlet 102 both located adjacent to the end of the fan 104 remote from a fan motor 105 drivingly connected to the fan. The air inlets 101 and 102 can be selectively opened and closed by means of a change-over damper 103 so that either fresh air or recirculated air can be sucked by the fan 104 into the duct 20.
An air-cooling heat exchanger formed by a refrigerant evaporator 21 and an air-heating heat exchanger formed by a heater core 22 are disposed in the duct 20 with the heater core 22 positioned downstream of the evaporator 21. The air from the fan 104 all flows through the evaporator 21. However, the heater core 22 is so disposed in the duct 20 that a bypass passage 24 is defined between the heater core 22 and the inner wall of the duct 20. An air-mixing damper 23 is provided in the duct 20 to adjust the ratio of distribution of air from the evaporator 21 to the heater core 22 and the bypass passage 24. When the air-conditioner is operated in cooling mode, the air passing through the evaporator is cooled thereby and flows through the heater core 22 and/or the bypass passage 24 at a distribution ratio determined by the air-mixing damper 23. The air flowing through the heater core 22 is heated by hot engine-cooling water flowing therethrough in heat exchange relationship with the air, whereas the air flowing through the bypass passage 24 is not heated but is at a low temperature. The heated air and the cooled air are mixed together in an air-mixing chamber 25 provided in the duct 20 downstream of the heater core 22. The air-conditioner is so controlled that the mixture of the heated and cooled airs is at a desired temperature level.
The downstream end of the duct 20 is divided into three outlets; namely, a ventilation air outlet 26, a heated air outlet 27 and a defrosting air outlet 28. A ventilation-defrosting change-over damper 31 and a heated-air damper 33 are disposed adjacent to the outlets 26-28 and are operatively linked to mode selection levers (not shown) on a control panel (not shown) so that the dampers 31 and 33 are pivotally moved to selectively open and close the outlets 26-28.
The automotive air-conditioner of the class discussed above is required to be as compact as possible so that the air-conditioner can be installed in a very limited space. At the same time, the air-conditioner must satisfy the requirements in respect of the air-blowing capacity and low level of noise produced during air-conditioning operation.